X-Git-Url: https://fleuret.org/cgi-bin/gitweb/gitweb.cgi?a=blobdiff_plain;f=mtp_graph.cc;h=48de3cac4d26049504eddb5b457fb7dafe8ddcd4;hb=1bafc06664224a632f4f607a23a8187f32a1f447;hp=e83c84869830b898af94965a9d35cf3815b657d0;hpb=a63e176f5b016f1d5a2a7b5101544430e5d3691e;p=mtp.git

diff --git a/mtp_graph.cc b/mtp_graph.cc
index e83c848..48de3ca 100644
--- a/mtp_graph.cc
+++ b/mtp_graph.cc
@@ -159,10 +159,10 @@ MTPGraph::MTPGraph(int nb_vertices, int nb_edges,
   _sink = &_vertices[sink];
 
   for(int e = 0; e < nb_edges; e++) {
-    _vertices[vertex_from[e]].add_leaving_edge(_edges + e);
+    _vertices[vertex_from[e]].add_leaving_edge(&_edges[e]);
     _edges[e].occupied = 0;
-    _edges[e].origin_vertex = _vertices + vertex_from[e];
-    _edges[e].terminal_vertex = _vertices + vertex_to[e];
+    _edges[e].origin_vertex = &_vertices[vertex_from[e]];
+    _edges[e].terminal_vertex = &_vertices[vertex_to[e]];
   }
 
   for(int v = 0; v < _nb_vertices; v++) {
@@ -173,9 +173,7 @@ MTPGraph::MTPGraph(int nb_vertices, int nb_edges,
   paths = 0;
   nb_paths = 0;
 
-  compute_dp_ranks();
-  for(int v = 0; v < _nb_vertices; v++) { _dp_order[v] = &_vertices[v]; }
-  qsort(_dp_order, _nb_vertices, sizeof(Vertex *), compare_vertices_on_distance);
+  compute_dp_ordering();
 }
 
 MTPGraph::~MTPGraph() {
@@ -189,83 +187,9 @@ MTPGraph::~MTPGraph() {
 
 //////////////////////////////////////////////////////////////////////
 
-void MTPGraph::compute_dp_ranks() {
-  Vertex *v;
-  Edge *e;
-  int tv;
-
-  // This procedure computes for each node the longest link from the
-  // source and abort if the graph is not a DAG. It works by removing
-  // successively nodes without predecessor: At the first iteration it
-  // removes the source, then the nodes with incoming edge only from
-  // the source, etc. If it can remove all the nodes that way, the
-  // graph is a DAG. If at some point it can not remove node anymore
-  // and there are some remaining nodes, the graph is not a DAG. The
-  // rank of a node is the iteration at which is it removed, and we
-  // set the distance_from_source fields to this value.
-
-  int *nb_predecessors = new int[_nb_vertices];
-  int *without_predecessor = new int[_nb_vertices];
-  int *new_without_predecessor = new int[_nb_vertices];
-  int nb_without_predecessor, new_nb_without_predecessor;
-
-  for(int k = 0; k < _nb_vertices; k++) {
-    nb_predecessors[k] = 0;
-  }
-
-  for(int k = 0; k < _nb_vertices; k++) {
-    v = _vertices + k;
-    for(e = v->leaving_edge_list_root; e; e = e->next_leaving_edge) {
-      tv = int(e->terminal_vertex - _vertices);
-      nb_predecessors[tv]++;
-    }
-  }
-
-  nb_without_predecessor = 0;
-  for(int k = 0; k < _nb_vertices; k++) {
-    if(nb_predecessors[k] == 0) {
-      without_predecessor[nb_without_predecessor++] = k;
-    }
-  }
-
-  scalar_t rank = 1;
-  while(nb_without_predecessor > 0) {
-    new_nb_without_predecessor = 0;
-    for(int l = 0; l < nb_without_predecessor; l++) {
-      v = _vertices + without_predecessor[l];
-      v->distance_from_source = rank;
-      for(e = v->leaving_edge_list_root; e; e = e->next_leaving_edge) {
-        tv = int(e->terminal_vertex - _vertices);
-        nb_predecessors[tv]--;
-        ASSERT(nb_predecessors[tv] >= 0);
-        if(nb_predecessors[tv] == 0) {
-          new_without_predecessor[new_nb_without_predecessor++] = tv;
-        }
-      }
-    }
-
-    swap(without_predecessor, new_without_predecessor);
-    nb_without_predecessor = new_nb_without_predecessor;
-    rank++;
-  }
-
-  for(int k = 0; k < _nb_vertices; k++) {
-    if(nb_predecessors[k] > 0) {
-      cerr << __FILE__ << ": The graph is not a DAG." << endl;
-      abort();
-    }
-  }
-
-  delete[] nb_predecessors;
-  delete[] without_predecessor;
-  delete[] new_without_predecessor;
-}
-
-//////////////////////////////////////////////////////////////////////
-
 void MTPGraph::print(ostream *os) {
   for(int k = 0; k < _nb_edges; k++) {
-    Edge *e = _edges + k;
+    Edge *e = &_edges[k];
     (*os) << e->origin_vertex - _vertices
           << " -> "
           << e->terminal_vertex - _vertices
@@ -283,7 +207,7 @@ void MTPGraph::print_dot(ostream *os) {
   (*os) << "        " << _source - _vertices << " [peripheries=2];" << endl;
   (*os) << "        " << _sink - _vertices << " [peripheries=2];" << endl;
   for(int k = 0; k < _nb_edges; k++) {
-    Edge *e = _edges + k;
+    Edge *e = &_edges[k];
     (*os) << "        "
           << e->origin_vertex - _vertices
           << " -> "
@@ -301,7 +225,7 @@ void MTPGraph::print_dot(ostream *os) {
 
 void MTPGraph::update_positivized_lengths() {
   for(int k = 0; k < _nb_edges; k++) {
-    Edge *e = _edges + k;
+    Edge *e = &_edges[k];
     e->positivized_length +=
       e->origin_vertex->distance_from_source - e->terminal_vertex->distance_from_source;
   }
@@ -313,7 +237,7 @@ void MTPGraph::force_positivized_lengths() {
   scalar_t max_error = 0.0;
 #endif
   for(int k = 0; k < _nb_edges; k++) {
-    Edge *e = _edges + k;
+    Edge *e = &_edges[k];
 
     if(e->positivized_length < 0) {
 #ifdef VERBOSE
@@ -456,7 +380,7 @@ void MTPGraph::find_best_paths(scalar_t *lengths) {
   // Put back the graph in its original state (i.e. invert edges which
   // have been inverted in the process)
   for(int k = 0; k < _nb_edges; k++) {
-    e = _edges + k;
+    e = &_edges[k];
     if(e->occupied) { e->invert(); }
   }
 }
@@ -504,6 +428,71 @@ int MTPGraph::retrieve_one_path(Edge *e, Path *path) {
   return l;
 }
 
+//////////////////////////////////////////////////////////////////////
+
+void MTPGraph::compute_dp_ordering() {
+  Vertex *v;
+  Edge *e;
+  int tv;
+
+  // This procedure computes for each node the longest link from the
+  // source, and abort if the graph is not a DAG, and order the node
+  // in _dp_order according to that value.
+
+  int *nb_predecessors = new int[_nb_vertices];
+
+  Vertex **already_processed = _dp_order, **front = _dp_order, **new_front = _dp_order;
+
+  for(int k = 0; k < _nb_vertices; k++) {
+    nb_predecessors[k] = 0;
+  }
+
+  for(int k = 0; k < _nb_vertices; k++) {
+    v = &_vertices[k];
+    for(e = v->leaving_edge_list_root; e; e = e->next_leaving_edge) {
+      tv = int(e->terminal_vertex - _vertices);
+      nb_predecessors[tv]++;
+    }
+  }
+
+  for(int k = 0; k < _nb_vertices; k++) {
+    if(nb_predecessors[k] == 0) {
+      *(front++) = _vertices + k;
+    }
+  }
+
+  scalar_t rank = 1;
+  while(already_processed < front) {
+    new_front = front;
+    while(already_processed < front) {
+      v = *(already_processed++);
+      v->distance_from_source = rank;
+      for(e = v->leaving_edge_list_root; e; e = e->next_leaving_edge) {
+        tv = int(e->terminal_vertex - _vertices);
+        nb_predecessors[tv]--;
+        ASSERT(nb_predecessors[tv] >= 0);
+        if(nb_predecessors[tv] == 0) {
+          *(new_front++) = e->terminal_vertex;
+        }
+      }
+    }
+    front = new_front;
+    rank++;
+  }
+
+  if(already_processed < _dp_order + _nb_vertices) {
+    cerr << __FILE__ << ": The graph is not a DAG." << endl;
+    abort();
+  }
+
+  delete[] nb_predecessors;
+
+  for(int v = 0; v < _nb_vertices; v++) { _dp_order[v] = &_vertices[v]; }
+  qsort(_dp_order, _nb_vertices, sizeof(Vertex *), compare_vertices_on_distance);
+}
+
+//////////////////////////////////////////////////////////////////////
+
 void MTPGraph::retrieve_disjoint_paths() {
   Edge *e;
   int p, l;